This invention relates to a highly sensitive Hall element.
The Hall element finds utility as an element for the measurement of magnetic fields and for the conversion of the intensity of a magnetic field into an electrical signal. The Hall element enjoys numerous notable advantages such as, for example, ability to permit measurement of electric fields without requiring direct contact, high reliability of performance and high speed of response. It has to date found utility in applications to ammeters, wattmeters, magnetic reproducing heads, multipliers, displacement transducers, tachometers, etc.
One of the present inventors has already proposed a method and apparatus for detecting magnetic bubbles by use of two or more Hall elements (U.S. Pat. No. 3,973,182).
As semiconductors which are usable as Hall elements in such applications, those made of InSb and InAs are known in the art. Recently, semiconductors of GaAs have come to find popular acceptance because of their ability to improve the temperature stability. When an electric current "I" is supplied and a magnetic field "B" is vertically applied to a Hall element made of a semiconductor having a Hall coefficient "R.sub.H " and a thickness "d", the Hall voltage "V.sub.H " to be obtained from the element is expressed by equation (1) given below. ##EQU1##
The sensitivity "K" of this Hall element is expressed by equation (2) and the Hall coefficient "R.sub.H " by equation (3) respectively. ##EQU2## where "e" is the electric charge of the electron and "n" is the electron concentration.
Enhancement of the sensitivity of the Hall element, therefore, has to date been attempted such as by selecting a semiconductor material having a high Hall coefficient, namely a semiconductor material of high purity, and by minimizing the thickness of the Hall element. Owing to the technical standards prevalent today, however, these measures invariably have their own limits.